Department of Food Science, Cornell University, Ithaca, NY 14853.
FrieslandCampina, Stationsplein 4, 3818 LE Amersfoort, The Netherlands; Food Quality and Design, Wageningen University and Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
J Dairy Sci. 2020 Dec;103(12):10986-11007. doi: 10.3168/jds.2020-18605. Epub 2020 Oct 9.
The ability of milk and concentrated milk to withstand a defined heat treatment without noticeable changes such as flocculation of protein is commonly denoted as heat stability. A heat treatment that exceeds the heat stability limit of milk or concentrated milk, which has a much lower heat stability, may result in undesired changes, such as separation of milk fat, grittiness, sediment formation, and phase separation. Most laboratory-scale batch heating methods were developed in the early 20th century to simulate commercial sterilization, and these methods have since been standardized. Heat stability studies have been motivated by different objectives during that time, addressing different processing issues and targets in the framework of available technology, legislation, and consumer demand. Although milk hygiene has improved during the last couple of decades, rendering milk less sensitive to coagulation, different standard methods suffered from poor comparability of results, even when comparing results for the same milk sample, indicating that unknown procedural steps affect heat stability. The prediction of heat stability of concentrated milk from the heat stability results of the corresponding unconcentrated milk for rapid quality testing purposes has been difficult, mainly due to different experimental conditions. The objective of this study is to review literature on heat stability, starting from studies in the early 20th century, to summarize the vast number of studies on compositional aspects of milk affecting heat stability, and to lead the way to the most recent work related to compositional changes in concentrates produced by membrane concentration and fractionation, respectively. Particular attention is paid to early and most recent developments and findings, such as the application of kinetic models to predict and limit protein aggregation to assess and describe heat stability as a temperature-time-total milk solids continuum.
牛奶和浓缩牛奶在不发生明显变化（如蛋白质絮凝）的情况下耐受特定热处理的能力通常被称为热稳定性。超过牛奶或浓缩牛奶的热稳定性极限的热处理，其热稳定性要低得多，可能会导致不期望的变化，如乳脂分离、粗糙感、沉淀形成和相分离。大多数实验室规模的批量加热方法是在 20 世纪早期开发的，用于模拟商业灭菌，此后这些方法已经标准化。在那段时间里，热稳定性研究的动机是不同的目标，在可用技术、法规和消费者需求的框架内解决不同的加工问题和目标。尽管在过去的几十年里，牛奶卫生状况有所改善，使牛奶对凝固的敏感性降低，但不同的标准方法在结果的可比性方面存在问题，即使比较同一牛奶样品的结果也是如此，这表明未知的程序步骤会影响热稳定性。浓缩牛奶的热稳定性预测从相应未浓缩牛奶的热稳定性结果中得到，但由于实验条件不同，这一直很困难。本研究的目的是从 20 世纪早期的研究开始，回顾关于热稳定性的文献，总结大量关于影响热稳定性的牛奶成分方面的研究，并为最近与膜浓缩和分级分别产生的浓缩物的成分变化相关的工作铺平道路。特别关注早期和最近的发展和发现，例如应用动力学模型来预测和限制蛋白质聚集，以评估和描述作为温度-时间-总牛奶固体连续体的热稳定性。
